For the purposes of this description, electrical apparatus will mean, in general, any electrical means or device whatsoever generally forming part of electrical installations in civil buildings and similar and usually intended to be mounted, for example built-in, on the walls of said buildings.
Therefore, this definition includes, but is not limited to, switches, power supply sockets, data network sockets, TV sockets, telephone sockets, pushbutton switches, change-over switches, regulating electrical devices in general, connectors, thermostats, timers, fuse-holders, ringers/buzzers, emergency lights for example removable, signaling lights for example step lights, displays for example LCD and similar.
As is known, many of the above-mentioned electrical apparatuses are usually installed on the walls using composite mounting structures, or groups of parts, generally including:
a box intended to be inserted into the wall;
an apparatus-holding mounting frame (or supporting frame) which can be fixed to the box and comprising a frame body surrounding an opening defining a mounting seat suitable to receive and hold one or more electrical apparatuses; and
a removable covering plate which can be fixed to the frame and provided with an opening so that the user can access, visually or manually, the electrical apparatuses installed on the supporting frame.
Various systems are known in the state of the art to fix an electrical apparatus to a supporting frame in such a way that it can be removed. For example, it is known to provide flexible tongues on two sides of the supporting frame opposite the mounting seat and suitable to engage with respective rigid teeth provided on opposite sides of an electrical apparatus intended to be fixed to the supporting frame. Said tongues must be sufficiently flexible to allow smooth attachment/detachment between the electrical apparatus and the supporting frame and, at the same time, they must be sufficiently rigid to guarantee adequate holding between the electrical apparatus and the supporting frame.
For this reason, the above-described fixing system of the prior art, even if widely used, in some cases presents a problem of fragility of the flexible fixing tongues, in other cases it is not such as to prevent accidental and unwanted detachment of the electrical apparatus from the supporting frame or dislodging of the electrical apparatus into the supporting frame and, therefore, towards the inside of the box built into the wall.